Note: This is obviously my profile, but the same step applies to yours.
I'm telling you to actually create a ROM hack first, then edit all the details after.
More often than not, people who want to make ROM hacks can't actually do it.
So it may do you good to prove that you can make one.
For starters, it may be good to just follow the levels given by the game.
If you want a difficulty hack, maybe +1 x (factor) to the levels given by the game, but you decide on the multiplication factor based on some arbitrary rule in your mind, such as amount of gym badges.
Asking for levels and teams isn't against the rules, but more often than not, others won't want to contribute when there is no indication that you can do deliver proper ROM hacks.
As I've said, many 'creators' want a ROM hack, but can't actually do it.